Individual's infected with the human immunodeficiency virus (HIV-1) frequently exhibit serious, progressive behavioral, cognitive and motor deficits (termed NeuroAIDS) in association with pathological changes (including gliosis, encephalitis and vacuolar myelopathy) in the brain. Current evidence strongly indicate the pathogenesis of this disorder (also known as NeuroAIDS) involves neurotoxic pathways mediated by: (1) HIV-1 related products e.g. the envelope protein gp120 and (2) products of the host response exemplified by cytokines such as IL-6, IFN- and TNF, release from activated macrophage/microglia and astroglia. Methamphetamine (METH) abuse which is frequently accomplished by significant acute and long-term neuronal damage is prevalent amongst HIV-1 infected individuals. We hypothesize here that the combination of these viral, host and METH insults produce additive or even synergistic actions that result in the worsening of the neuropathological sequelae and an accelerated progression to the functional neuropsychiatric deficits of NeuroAIDS. To determine the nature and mechanisms by which the central stimulant drug METH interacts with host-derived and HIV-1 related products to influence the degree and progression of structural and functional central nervous system (CNS) injury. Dysregulated peripheral immune function resulting from HIV-1 infection as well as infection from additional infectious agents is observed in individuals with AIDS. Therefore, we will define the interactions between METH and peripheral immune stimulation (achieved by intraperitoneal injection of the potent immune stimulant lipopolysaccharide) to influence the severity and progression of both CNS host responses and neuropathology. Transgenic mice with cerebral expression of IL6, TNF-, TNF- or gp120 recapitulate many of the structural and functional features of NeuroAIDS and will be used in the proposed studies to elucidate the interactions between METH and the central production of host- or HIV-1- related products to the development and progression of CNS host responses and neuropathology. Finally, transgenic mice with over-expression of Cu/Zn superoxide dismutase (SOD) or deficient expression of tissue-type plasminogen activator (tPA) that may underlie the pathogenic interactions between METH and products of the host response or HIV-1. This research plan integrates analysis of drug effects on the CNS as it relates to components of HIV disease progression is an important question for pre clinical and clinical research, as substance abusers have a high risk for exposure to the virus. The proposed studies should go far in identifying critical viral- and host-derived factors associated with increased susceptibility to the pathological effects of drugs of abuse such as METH and consequent neurotoxicity.